import java.awt.*;
import java.awt.event.*;
public class useObject extends Frame implements ActionListener
{
     static useObject frm = new useObject();
     static Panel pan1 = new Panel();
     static Panel pan2 = new Panel();
     static Button but1 = new Button("第一页");
     static Button but2 = new Button("上一页");
     static Button but3 = new Button("下一页");
     static Button but4 = new Button("最后页");
     static CardLayout crd = new CardLayout(5,10);
     public static void main(String[] args )
        {
            frm.setLayout(null)    ;
            frm.setTitle("操作事件");
            pan2.setLayout(new GridLayout(1,4));
            pan1.setLayout(crd);
            frm.setSize(200,350);
            frm.setResizable(false);
            but1.addActionListener(frm);
            but2.addActionListener(frm);
          but3.addActionListener(frm);
          but4.addActionListener(frm);
          pan1.setBounds(10,20,270,200);
          pan2.setBounds(10,220,270,20);
          frm.add(pan1);
          frm.add(pan2);
          Label lab1 =new Label("第一页",Label.CENTER);
          TextField tex = new TextField("卡片式布局CardLayout",18);
          pan1.add(lab1,"n1");
          pan1.add(new Label("第二页",Label.CENTER),"n2");
          pan1.add(tex,"n3");
          crd.show(pan1,"n3");
          pan2.add(but1,"d1");
          pan2.add(but2,"d2");
          pan2.add(but3,"d3");
          pan2.add(but4,"d4");
          frm.setVisible(true);
        }     
        public void actionperformed(ActionEvent e)
            {
                Button but = (Button)e.getSource();
                if (but == but1) crd.first(pan1);        
                else if (but == but2) crd.previous(pan1);
                else if (but == but3) crd.next(pan1);
                else crd.last(pan1);
            }
}

为什么运行时说是useObject类不是抽象类，而且没有覆盖Java.awt.event.listener中的actionperformed（）方法啊？希望高手给我解决一下，谢谢。

谢谢高手，原因正在这里，我找了好长时间都没有找出来，谢谢。